fix modify the way of the command 'yum remove xxx', e.g. docker-selinux and docker-engine-selinux packages

* failed

* version_compare

* succeeded

* skipped

* success

* version_compare becomes version since ansible 2.5

* ansible minimal version updated in doc and spec

* last version_compare

* Added changes to clean up orphan containers and reload docker & kubelet directories.

* Added new files for cleaning up orphans and docker & kubelet directories

* Added new lines at the end of these files

* removed the trailing whitespaces from main.yml and clean-up.yml

* Updated as per the review comments

* Updated as per the review comments

* Removed service_facts and package_facts because they are not supported in ansible 2.4.0

* Corrected yaml syntax errors

* Removed the use of json_query filter and utilized selectattr

* Removed trailing spaces

* Changed the default value of docker_clean_up to false

* Added Changes to only include cleanup-docker-orphans.sh

* Reverted back changes done inside handler.

* Removed trailing spaces and made default value of docker_orphan_clean_up as true

* Reverted the default value of docker_orphan_clean_up as false

* Made the docker clean up as drop in

* Made the docker clean up as drop in

* Reverted the value of boolean docker_orphan_clean_up to false

* Fix bootstrap_os/ubuntu idempotency

* Update bastion role

* move container_engine in sub-roles

* requires ansible 2.5

* ubuntu18 as first CI job